A ram boring machine of this kind is known from German Patent 21 57 295. It is mainly used to lay supply lines such as, for example, water pipes or cables beneath roads or embankments or other buildings and obstacles without having to tear up the surface of the road or ground at the same time. The way this is done is that the ram boring machine, in moving forwards in the ground, pushes the earth to the side and leaves a tunnel behind it into which the supply line is simultaneously or subsequently drawn. The impact tip serves to shatter stones or other obstacles during the forward movement of the ram boring machine and to push them aside, i.e. drive a passage for the housing moving up behind. However, it is not always possible to prevent the ram boring machine from moving out of the desired direction when it strikes an obstacle.
A ram boring machine whose course can be directed is known from German Offenlegungsschrift 22 42 605 and has a tubular, curved extension on its rear end which is also provided with curved guide surfaces as a means of obtaining a curved boring course in the earth. It is necessary to produce curved bores of this kind if, for example in narrow roads with narrow sidewalks, it is not possible to dig out starting and finishing pits at least deep enough for the ram boring machine to be set up horizontally in the starting pit and, in addition, still pass underneath all the other lines lying beneath the surface of the road. The rigid deflectors enable a curved boring course to be obtained that is decided before the machine is started, but during operation the direction cannot be influenced.